Fuel sprays in current combustion systems of gas turbine engines are from discrete fuel injectors. Air introduced through fuel injectors and adjacent air swirlers needs to be mixed rapidly with the fuel spray for combustion, and for gaseous and smoke emissions control. The frame fronts in the combustion region are around stoichiometric level and hence generate high temperature zones in the combustor, leading to high nitrogen oxide emissions. Any unmixedness in the fuel-air mixture will result in high smoke and pattern factor, which are not desirable for the environment and hot-section durability.